While it sounds like you know what you’re doing, there’s nothing worse than DIY electricians who DON’T know what they are doing.
Mr mm nearly got taken out by backfeed because some idiot before us, ran TWO circuit breakers to the same light. So mr. mm ha closed off the one circuit and started to work and wow howdy, there was a spark, a loud snap, and he got quite a jolt.
What goes on in the minds of most amateur non-electricians who think they can do their own work is beyond me but we and my son have seen some atrocities that somehow miraculously, did not burn the house down.
In my non-professional opinion, it would likely be easier and less time to just rerun everything than to try to figure out what’s going on and hope that you caught it all. That’s what we’ve resorted to after enough wasted time trying to figure out just what the heck is going on.
Like I said in my post, I was an electricians apprentice years ago, and I gladly took a step back and called a licensed professional when I ran into something I’d not seen. I used to do commercial new construction and worked with large generators, transfer switches, and general wiring, so this stuff isn’t new to me, but my house is new to me.
The end result here is that everything is put back the way it is with the notable exception of a Romex run that’s no longer end-to-end but spliced. I’m just questioning the little amount of voltage on a ground, which isn’t normal in a properly wired home.